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Objective: To examine the evidence addressing the management of X-linked hypophosphatemia (XLH) in children to inform treatment recommendations., Methods: We searched Embase, MEDLINE, Web of Science, and Cochrane Central up to May 2023. Eligible studies included RCTs and observational studies of individuals less than 18yrs with clinically or genetically confirmed XLH. Manuscripts comparing burosumab to either no treatment or conventional therapy (phosphate/active vitamin D) or evaluating conventional therapy to no treatment were included. Two reviewers independently determined eligibility, extracted data, and assessed risk of bias (RoB). GRADE methodology was used to assess evidence certainty., Results: We screened 4,114 records and assessed 254 full texts. One RCT and one post-hoc study proved eligible when comparing burosumab to conventional therapy or no treatment. The open-label RCT was at high RoB, with certainty of evidence ranging from moderate to very low. Burosumab, compared to conventional therapy, probably prevents lower limb deformity and improves physical health QoL(moderate certainty). Burosumab may increase height and enhance the burden of symptoms related to chronic hypophosphatemia(low certainty). Burosumab probably increases Treatment-Emergent Adverse Events (moderate certainty) and may increase dental abscesses (low certainty). One observational study assessing conventional therapy versus no treatment was at high RoB providing very low certainty evidence regarding the impact of conventional therapy on final height., Conclusion: Our review indicates that burosumab likely provides benefits to children by preventing lower limb deformity and improving physical health QoL while potentially increasing height. However, burosumab may also increase adverse events. Our review found limited evidence regarding the impact of conventional therapy compared to no treatment on final height. Further research is required to understand the long-term effect of medical therapy in children., (© The Author(s) 2025. Published by Oxford University Press on behalf of the Endocrine Society.)

Objective: To examine the highest certainty evidence addressing the management of X-linked hypophosphatemia (XLH) in adults to inform treatment recommendations., Methods: We searched Embase, MEDLINE, Web of Science, and Cochrane Central up to May 2023. Eligible studies included RCTs and observational studies of individuals 18+ with clinically or genetically confirmed XLH. Manuscripts comparing burosumab to no treatment or conventional therapy (phosphate and active vitamin D) and conventional therapy to no treatment were included. Two reviewers independently determined eligibility, extracted data, and assessed risk of bias (RoB). GRADE methodology was used to assess evidence certainty., Results: We screened 4,114 records, after removing duplicates, and assessed 254 full texts. One RCT and two observational studies were eligible. The RCT of burosumab versus no treatment had low RoB. Burosumab probably improves pain from fracture/pseudofracture healing (moderate certainty) but has little or no impact on direct pain measures (moderate certainty). Burosumab may reduce the need for parathyroidectomy (low certainty) but has little or no impact on fatigue (high certainty), stiffness (moderate certainty), and mobility (low certainty) over 24 weeks. Burosumab may increase dental abscess risk (low certainty). Indirect evidence comparing burosumab to conventional therapy provided low certainty regarding burosumab versus conventional therapy. Two observational studies on conventional therapy versus no treatment had high RoB and very low certainty regarding the impact of conventional therapy on patient-important outcomes., Conclusion: No formal comparisons between burosumab and conventional therapy in adults exist. Evidence for conventional therapy versus no treatment is very uncertain. Our review highlights the need for more data on the long-term effects of burosumab and conventional therapy on patient-important outcomes in adult patients with XLH., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Endocrine Society.)

Context: X-linked hypophosphatemia (XLH) is a rare genetic bone disease affecting both children and adults, with oral manifestations such as spontaneous dental infections. The main treatments for XLH are conventional treatment (CT) with oral phosphate salts and active vitamin D supplementation, and burosumab, an antibody targeting Fibroblast Growth Factor 23 (FGF23). While the beneficial effect of CT on oral manifestations is established, the effect of burosumab on oral health is unknown, especially in adults., Objective: We aimed to compare the oral health (number of missing or endodontically treated teeth and presence of periodontal disease) and incidence of endodontic infections of adult patients with XLH according to their treatment's modalities (no treatment, CT, or burosumab)., Methods: This was achieved through a single-center, retrospective analysis of oral health data from 44 patients who had undergone dental monitoring for at least 6 months., Results: Oral health varied according to the proportion of their adult life spent under treatment for XLH and the incidence of dental infections during follow-up was influenced by the type of treatment received. There was a 55.9% reduction of infections during CT and an 86.4% reduction during burosumab treatment compared to periods with no treatment (P < 0.0001). Comparing treatment and non-treatment periods within the same patient showed a strong association between burosumab treatment and decreased infection incidence (0.006 vs 0.09 infection per month, P<0.01)., Conclusions: We observed that adults with XLH treated with burosumab developed fewer endodontic infections during dental follow-up than patients who were untreated or received CT., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com. See the journal About page for additional terms.)

The identification of the molecular mechanisms controlling the degradation of regulatory proteins in mesenchymal stromal cells (MSC) may provide clues to promote MSC osteogenic differentiation and bone regeneration. Ubiquitin ligase-dependent degradation of proteins is an important process governing cell fate. In this study, we investigated the role of the E3 ubiquitin ligase c-Cbl in MSC osteoblast differentiation and identified the mechanisms involved in this effect. Using distinct shRNA targeting c-Cbl, we showed that c-Cbl silencing promotes osteoblast differentiation in murine and human MSC, as demonstrated by increased alkaline phosphatase activity, expression of phenotypic osteoblast marker genes (RUNX2, ALP, type 1 collagen), and matrix mineralization in vitro. Coimmunoprecipitation analyses showed that c-Cbl interacts with the transcription factor STAT5, and that STAT5 forms a complex with RUNX2, a master transcription factor controlling osteoblastogenesis. Silencing c-Cbl decreased c-Cbl-mediated STAT5 ubiquitination, increased STAT5 protein level and phosphorylation, and enhanced STAT5 and RUNX2 transcriptional activity. The expression of insulin like growth factor-1 (IGF-1), a target gene of STAT5, was increased by c-Cbl silencing in MSC and in bone marrow stromal cells isolated from c-Cbl deficient mice, suggesting that IGF-1 contributes to osteoblast differentiation induced by c-Cbl silencing in MSC. Consistent with these findings, pharmacological inhibition of STAT5 activity, or neutralization of IGF-1 activity, abrogated the positive effect of c-Cbl knockdown on MSC osteogenic differentiation. Taken together, the data provide a novel functional mechanism by which the ubiquitin ligase c-Cbl regulates the osteoblastic differentiation program in mesenchymal cells by controlling Cbl-mediated STAT5 degradation and activity., (Copyright © 2013 AlphaMed Press.)